Friction speed gear



May Z9, 1951 A. GIORGI 2,555,079

FRICTION SPEED GEAR Filed Nov. l5, 1946 Patented May 29, 1,7951

Ury-Iren PAT-ENT oF-Ficl:

'Fmc'riczissn GEAR Application November 15, 194,6', Serial No. 709,834Iii Italy Nvembf 23, 1945 V2 anims. (ci. 7er-*199) This inventionrelates to a 'continuously acting progressive friction speed gear whichconsists substantially of two pairs of coned discs, lthe conicalsurfaces of each pair being kept pushed the one towards the other by asuitably applied elastic action in accordance with the average power tobe transmitted and which may give a multiplication or a reduction ofthel speed.

A connecting device is provided Ywhich transmits the rotating motion ofthe drivingv pairof conical discs (one at least 'of which vis keyed tothe vdriving shaft but preferably both) tol the driven pair of conicalvdiscs attached in-an analogous manner to H they driven shaft. Thistransmitting device preferably is comprised -by a cylindrical disc thetwo" flat surfaces of which are simultaneouslyin frictional engagement,by their 'peripheries, withfthe conical surfaces -of the driving cones,and also at the same time, in a diametrically opposite position, infrictional engagement with vthe conical surfaces of 4the cones to bedriven.

The transmitting deviceis mounted to move or slide by means'whlch causeits shaft tofmo've parallel to itself. lIn this way the gear ratio willcontinuously and progressively or regressively be caused to vary, itbeing `understood that the axes of the driving shaft and the drivenshaft are parallel to eachother as well asparallel to that of the shaftof the transmitting device.

To carry out a variation of the gear ratio it is necessary to vary,whilst still'keeping the axes of` the various shafts parallel, thedistance between the axis of the transmitting rdevice and the two otheraxes. In some respects, the most favourable solution is when all threeaxes come in the same plane but this is not necessary vas the axis ofthe transmitting device may come in a plane displaced out of the planeof the other two axes. In practice, the distance variations between theaxes ofthe driving and drivenlshafts in relation to the axis of theshaft of the transmitting device, which latter isdisposed in a positionintermediate the two former, is obtained by moving the axis of the shaftof the transmitting device while the yother axes remain fixed, althoughin some cases the axis of the shaft of the transmitting device may bexed and the other axes movable.

The shifting of the transmitting deviceV axis towards the axis of thedriving shaft effects a gearing-down of the transmitted speed, and theshifting of the axis of the `transinittingv device towards the drivenshaft effects of "gearingfliip of `the transmittedspeed. 'The'iariationof 'the xed axiswhilst fthe other end'is carried byf-a nut engaged by ascrewed spindle rotatedby means of a hand 'wheel' but heldfromlaxialmovement. To reduce the friction as-'well a's the wear-"of the edges andsurfaces vin `frictional driving or driven oo'ntact, it is*preferred--toin-- crease' the pairs of conical discsbyadditional coaxialv pairsofconical discsA with interposed springs 'to 4compensate for thevariation in "friction' pressures. In thisl manner' the" adherencefriction between the'diiferent pairs of conical discs and thetransmitting device will bejthe Sarnejas theadherence -friction betweenthe transmitting device and the different conical discssupported by thedriving shaft; moreover, at'each such individual driving contactv pointthe value of the frictional adhesion will be Athe same.

' The' accompanying drawings showt an" embodi; ment of the inventionhaving four pairs of conical' discs, namely two pairs on the drivingshaft and two"pairs on 'thedriven shaft with the' interposition of oneYcylindrical transmitting disc for each 'two pairs of'conical discs'(one pair bn the driving shaft and one pair 'on' vthe driven shaft) Inthe drawings:

Fig'. 1 is a somewhat diagrammatic crosssectional plan of vthe geartaken in' a'general plane' which includ'esthe axes ofthe driving anddriven shafts, showing the transmitting discs shifted towards thedriving shaft, thatis to say inthe condition where the' parts act vas aspeed ferner.

UFig'.Y 2 shows a similar view'of Fig.' 1, but the trailsrnittingAshaft' ismoved towards thedriven shaft,` that is, in the condition vofVacting asa speed'multiplier.

Fig. 3 sli'rfiwsasomewhat` diagrammatic Aside elevation' of Fig.1"coup`led with'the 'controlgean and f Fig. 4 shows a vieW similarto'Fig. 3 but of rig; 2.

In connection'with the drawings, the"c`orid tiniious"speed variationdevice shown therein consists Vof friction discs` aliccntond'f'positiveiy by the driving shaft and composed by four pairs ofconical discs, A-B and C-D, with facing conical surfaces and the membersof each pair pushed the one towards the other by the stress of helicalcompression springs E. The centrally situated springs act at the sametime on the disc B of one pair and on the disc A of the other pairlocated on the driving shaft F and on the disc D of one pair and thedisc C of the other pair on the driven shaft G; both the driving anddriven shafts have splines or keyways for the engagement of the conicaldiscs.

Between the pairs of conical discs A-B on the driving shaft F and theconical discs C`-'D on the driven shaft G, there are interposed thetransmitting discs H each of which is engaged by four conical discs,that is to say, by a pair of conical discs on the driving shaft and apair of conical discs on the driven shaft, the whole in such manner thatthe driving shaft F can transmit its power to the driven shaft G.

The pressure of the springs E pushes the conical discs of each pair A-Band C-D the one towards the other, the discs sliding on the driving ordriven shaft as the case may be. The above pressure consequently alsoholds the cylindrical disc D in a steady manner in the somewhat V gapsformed between the pairs of discs, so that the consequent frictionalgrip is sufficient to transmit the power from the driven to the drivingshaft.

In the position shown by Fig. 1 the transmitting discs H are pushedtowards the driving shaft F and away from the driven shaft G. The twodiscs of each pair of discs A-B on the driving shaft are separated fromeach other and consequently the pressure of the springs E is increasedwhilst the two discs of each pair of discs C--D on the driven shaft arebrought nearer to each other and consequently the pressure of thesprings E is decreased.

In the position shown in Fig. 1 the discs H rotate on a circle of smalldiameter near the apices of the conical discs A-B on the driving shaft Fand on a larger diameter nearthe bases of the conical discs C-D on thedriven shaft G. The speed of the driven shaft G therefore will diminish,or in other words the device will work as a speed reducer.

In the position shown in Fig. 2, the transmitting discs H are pushedtowards the driven shaft G and away from the driving shaft F and theopposite result is obtained. There will be an increased speed becausethe transmitting discs. H will rotate on the bases of the conical discsA-B of the driving shaft F where the diameter is larger and will rotatetowards the apices of the conical discs C-D of the driven shaft'G whosediameter is smaller; the device therefore works as a speed multiplier.

The transmitting discs H rotate on a spindle I mounted in a lever systemL the axis of which is located in the point M (Figs. 3 and 4) to permitthe transmitting disc to be shifted freely towards both the drivingshaft F and the driven shaft G. Acting as above, a diminishing as Wellas an increasing of the driven shaft speed can be obtained accordingly.The shifting movement is realised by means of a nut N engaged with ascrewed spindle O held from axial movement but rotatable by a hand WheelP.

The whole system is housed in a metal casing, preferably of aluminium,forming a rigid support for all the moving parts which where requisiteare mounted in ball bearings. The conical 4 1 l discs A-B and C-D aswell as the transmitting discs are of best special converted, temperedand rectified steel, running in an oil bath contained in the casing.

The variation device can rotate in both directions. The elastic systemconstituted by the springs E, which has been chosen, permits themounting of a greater number of pairs of corneal discs A-B and C-D onthe driving and driven shafts respectively, as well as a greater numberof transmitting discs H on the spindle I, to permit high powers to betransmitted, which is not possible with other already known systemsapplied for the same purposes.

The elastic system of springs E which regulates the contact adhesionbetween the conical discs A-B and C-D and rthe transmitting discs H,gives the advantage of an increased adhesion by friction when the radiusof rotation becomes small Whilst the peripherie strain increases.Similarly, the adherence as well as the friction will diminish with anincreased radius of rotation and smaller peripherie strain. This makesfor slight wear and tear of the device and gives longer life and greatefficiency.

As will be realised, the above-described speed gear gives the advantageof eliminating belts, chains, flat discs and the like as generallyadopted in other speed variation systems having pairs of conical discsin co-operation with transmitting parts consisting of rollers or chains.

The invention is not limited to the precise forms or details ofconstruction herein described, as these may be varied to suit particularrequirements.

What I claim and desire to secure by Letters Patent of the United Statesof America is:

l. A progressive friction speed gear comprising two main shafts, aplurality of similar pairs of cone discs slidably carried in sequence byand rotatably rigid with each shaft, the number of pairs on each shaftbeing the same and the cone discs of each pair having their conicalsurfaces facing one another, a coil spring inserted between the outersurface of each disc of each pair and the outer surface of the disc ofthe adjacent pair facing the outer surface of the first disc considered,a collar rigid with each end of each main shaft at either end thereof,further coil springs inserted between the inner surface of each collarand the outer surface of the outer disc of the pair of discs nearestsaid collar, an auxiliary shaft parallel with the two main shafts andbetween same and lying substantially in the plane thereof, means forshifting said auxiliary shaft substantially in the plane of the twofirst shafts, substantially flat discs rigid with said auxiliary shaftsand the number of which is equal to that of the pairs of discs on eitherof the main shafts, said discs being adapted to engage operatively thecooperating conical surfaces facing one another in the correspondingpair of discs on each main shaft, the location of said auxiliary shaftwith reference to the main shafts defining the radius of contact of thediscs on either shaft with the outer operative edge of the flat discconsidered.

2. A progressive friction speed gear comprising two main shafts, aplurality of similar pairs of cone discs slidably carried in sequence byand rotatably rigid with each shaft, the number of pairs on each shaftbeing the same and the cone discs of each pair having their conicalsurfaces facing one another, a coil spring inserted between the outersurface of each disc of each pair and the outer surface of the disc of1the adjacent pair facing the outer surface of-vthe rst disc considered,a collar rigid with eachend of each main shaft at either endthereof,'ffurther coil springs inserted between the inner surface ofeach c01- lar and the outer surface ofthe outer disc of the pair ofdiscs nearest said collar, an auxiliary shaft parallel with the two mainvshafts and between same and lying substantially in the plane thereof,an arm pivotally carrying said auxiliary shaft and a screw and nutarrangement for controlling the displacement of said arm in a planeperpendicular to the two main shafts for shifting the auxiliary shaftsubstantially in the plane of said main shafts substantially flat discsrigid with said auxiliary shaftsl and the number of which is equal tothat of the pairs of discs on either of the main shafts, said discsbeing adapt-ed to engage operatively the cooperating conical surfacefacing one another in the corresponding pair of cone discs on each mainshaft, the location of said auxiliary shaft with reference to the mainshafts dening the radius of contact of the discs on either shaft withthe outer operative edge of the fiat disc considered.

ANTONIO GIORGI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

